This invention relates generally to a camera using a film cartridge, and more particularly to a device for preventing tilting of the film cartridge in the camera.
An automatic film-sensitivity setting device and an automatic filter change-over device have been proposed as means for detecting a signal from a film cartridge to automatically operate some type of camera component. With the device of the type described, a signal element is provided as a signal detecting means on a film cartridge, while a detecting member which is urged so as to engage the signal member is provided in the camera, whereby upon charging the film cartridge into the camera, the detecting member is brought into engagement with the signal element to detect a signal.
However, with the aforesaid arrangement, the detecting member maintains its biasing force on the cartridge so as to thereby possibly cause the film cartridge to tilt.
In other words, when the film cartridge is fixed in position, it is urged toward the side of an aperture by means of a pressure plate provided on a back cover, after being charged in the camera. A relatively weak spring force is therefore provided for the pressure plate because of the strength of the film cartridge and the light-shielding requirement for a cartridge retaining chamber of the camera, while much stronger spring force is exerted on the detecting member for operating components such as a film sensitivity setting member, a filter and the like, accurately and rapidly. Accordingly, the spring force of the detecting member overcomes the spring force of the pressure plate, thereby tilting the film cartridge when charged into the camera.
Therefore, the spring force may tilt the cartridge back and forth along the optical axis of the camera relative to an exposure plane thereby resulting in an unclear or defocused portion in part of an image on the film due to an improper back focal distance. In addition, if the cartridge tilts in a vertical direction of a camera (in a direction describing a circle around the optical axis), an image results which tilts relative to a frame of the film.